Method and apparatus for dovetailing articles of wood



Oct. 8, 1935. v c. P. ASPELUND 2,016,620

METHOD AND APPARATUS FOR DOVETAILING ARTICLES OF WOOD Filed July 5, 19532 Sheets-Sheet i 75 73 74 72 79 7'2 flr 0. P a e/m6? METHOD ANDAPPARATUS FOR DOVETAILING ARTICLES OF WOOD c P. ASPELUND 2 Sheets-Sheet2 Filed July 5, 1955 I I l I I I I I Patented Oct. 8, 1935 UNITED STATESPATENT OFFICE METHOD AND APPARATUS FOR DOVE- TAILING ARTICLES OF WOODCarl Pedersen Aspelund, Reykjavik, Iceland 7 Claims.

The present invention relates to a method for dovetailing articles ofwood and the invention is mainly distinguished in that the dovetailslots may be cut in a single operation simultaneously in both halves andhalf or wholly concealed as desired.

The invention also comprises a machine by which the method may becarried into effect and said machine is illustrated in the accompanyingdrawings in which:

Fig. 1 is a front view of the machine.

Fig. 2 is a side view of the same.

Fig. 3 is a vertical section through the driving mechanism of themachine.

Fig. 4 is a plan view of the same with parts broken away.

Fig. 5 is a front view of two wood pieces during the dovetailingoperation.

Fig. 6 is a cross section and Fig. 7 a plan view of the same.

Fig. 8 illustrates a cross sectional view of the pieces assembled,

Fig. 9 is a view corresponding to Fig. 6 illustrating a somewhatmodified embodiment.

Figure 10 is a detail view of the eccentric mechanism shown in crosssection, and

Figure 11 is a plan view of the same.

In the drawings denotes legs which support a. table 2 in which a slide 3is arranged movable in the longitudinal direction of said table. Theslide 3 is provided with rests 4 and 5 (Figure 3) and clamping devicese. g. screws 6, 1, by means of which two wood pieces 8, 9 may be securedat right angle to each other as shown.

On the front side ofthe table 2 are secured bearings It for verticallydisposed shafts H to the upper ends of which are secured plates l2 eachprovided with bearings l3 for a cutter shaft M. The shafts H! are each,on the end which is situated nearest to the shaft I I, provided with apulley l5 which by means of a belt I6 is driven from pulleys H on ashaft |B journalled in the legs I. The shaft I8 may be rotated in anyconvenient manner.

The shafts M are at their inner ends provided with cutters IS, the shapeand use of which will be described below.

On the front side of the table 2, at the middle between the bearings I0,is secured a bearing 50 for a vertical shaft 2|, which on its lower endis provided with a worm-wheel 22, coacting with a worm '23 on ahorizontal shaft 24, which is journalled in the legs I. The shaft 24 isdriven by means of a pulley 24' and belt 25 from a pulley 26 on theshaft I8.

of the catch 3| is provided a stopper 33 swing- 10' ably supported on apin- 34 connected to the table 2. The stop-per 33 meshes with the rack32 and serves to prevent undesired displacement of the slide 3 to theleft in Fig. 1. In order to hold the slide 3 pressed into engagementwith the stopper 15 33, the slide is acted upon by a weight 36 suspendedby means of a wire 35.

On the pin 30, which is secured to the arm 29, are pivotally secured twoarms 31, each of which by means of a pin 38 is pivotally connected with20 the outer ends of arms 39, 39, the other ends of which are secured tothe swingable plates |2, |2 respectively.

The edge portions of the work pieces 8 and 9, which are to bedovetailed, are rounded to a radius which approximately corresponds tothe radius of the cutters l9, and the pieces 8, 9 are clamped inposition into the machine with the rounded surfaces, facing each otheras shown in Fig. 6. With the pieces clamped in said position, the axesof the cutter shafts coincide with the plane in which the pieces toucheach other.

In rotating the shaft IS, the shafts M with the cutters H! are rotatedand simultaneously the shaft 2| is rotated by means of the worm 23 and 5worm-wheel 22 in the direction indicated by the arrow in Fig. 4. Duringthis operation the excentric pin 30, by means of the arms 31 and 39,swings the plate i2 and thereby the cutters I4 towards the work pieces8, 9, whereby inclined 40 slots are cut in the same. One of the cuttersI9 produces inclined slots a and the other cutter corresponding slots b,which are inclined in a direction opposite to that of the slots a. 1 Inorder to obtain slots of the necessary depth the cutters must be movedtowards the work pieces until the middle point of the cutter coincideswith the foremost limitation line of the pieces, as shown in Fig. 6. Thedistance at between the cutters I9 (Fig. 7) corresponds to the pitchof'the slots or a multiple of the same and the inclination of thecutters determines the proportion between the inner and outer width ofthe slots. In order to make the bottom of the slots as even as possiblethe teeth of the cutters are bevelled outwardly corresponding to theinclination of the cutters in relation to the work pieces.

By the continued rotation of the shaft 2| the plates l2 with the cuttersl9 are swung outwardly at the same time as the catch 3| moves to theleft on the rack 32 and during its return meshes with a tooth andcarries the slide 3 to the right a distance corresponding with the pitchof the dovetail slots, whereupon the whole operation is repeated. Duringthe return of the catch, the slide 3 is held resting against the stopper33 by means of the weight 36. At the start of the operation the slide 3may be released and carried to the left by releasing the stopper 33.

The width of the cutters I9 are preferably chosen corresponding to thenarrowest width of the dovetail slot and when both cutters, by the abovedescribed displacement, in succession are inserted in the work pieces atthe same point, they will, owing to its inclination, form in crosssection dovetail-shaped slots, the bottom of which are bounded by arcsof circles.

When the pieces 8, 9 have been worked in their entire length by bothcutters, the pieces may be locked together, as shown in Fig. 8.

In order to make the concealing or covering thicker the pieces 8, 9 areremoved somewhat from each other asshown in Fig. 9, the axes of thecutter shafts then coincide with the middle plane between the pieces.

In dovetailing wood pieces of different thickness it may be suflicientin connection with minor variations to shift in new cutters and adjustthe cutter shafts, as the width of the slots and the angle ofinclination may be altered to some extent without replacement of theexcenter mechanism and the rack. For greater variations in woodthickness the excenter mechanism and contingently also the rack must bereplaced. The feeding movement of the catch 3! may be adjusted by anadjustable cover plate which limits and determines the point ofengagement between the catch and the rack.

As will be understood the details of the machine shown and described maybe varied in many Ways without departing from the scope of theinvention, if only the described relative movements between the cuttersand the work pieces are provided in the longitudinal direction of thepieces as well as at right angle to the same.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. A method for treating a structure member to provide slots fordovetailing purposes, consistin in providing the member with a convexlyarcuated edge, then cutting slots with concavely arcuated bottomsurfaces, one slot being cut in the edge of the member at an acute angleto one side of a line normal to the edge of the member and another slotbeing cut entering the member coincidental with the first slot at anacute angle to the other side of a line normal to the edge of the memberto form a single dovetail slot.

2. A method for treating a structure member to provide slots fordovetailing purposes, consisting in providing the member with a convexlyarcuated edge, then cutting slots with concavely arcuated bottomsurfaces complemental to the convexly arcuated edges of the members, oneslot being cut in the edge of the member at an acute angle to one sideof a line normal to the edge of the member and another slot being Cutentering the member coincidental with the first slot at an acute angleto the other side of a line normal to the edge of the member to form asingle dovetail slot.

3. A method for treating a pair of wooden structure members to provideslots for dovetailing purposes,'consisting in providing the two memberswith convexly arcuated edge portions for making dovetail slots therein,said edges being rounded according to a circular arc with the sameradius as that of the cutters to be used, then placing the members at aright angle to each other with their rounded edge portions directedtowards and symmetrically in relation to the cutter axes, then cuttingthe slots in said edge portions simultaneously, the cutters being duringthe cutting operation arranged in such an angular relation to thelongitudinal axes of the edge portions that slots of a dovetailedcrosssection are formed, said slot bottoms being defined by acylindrical surface with the same radius as that of the first-namedrounded edge portions.

4. A method for treating structure members to provide slots fordovetailing purposes consisting in arranging two members at right anglesto each other, moving said members intermittently in a longitudinaldirection, moving a cutting tool in a direction toward said members soas to cut a slot in the edges of the members at an acute angle to oneside of a line normal to the edges of the members when the members arestationary and finally moving a second cutting tool toward said membersto successively enter the slots at the same acute angle to the otherside of said normal wherebyto provide dovetail slots.

5. A machine for cutting slots into the edges of structure members fordovetailing purposes comprising a table, a pair of disc-shaped cutterwheels mounted on the table in opposite relation to one another withtheir axes at an acute angle to the member edges and at an obtuse angleto one another, a slide for carrying and supporting a pair of structuremembers at right angles to each other mounted on the table, means forperiodically moving the cutters in a horizontal arc toward and away fromthe members at coincident spots and means for actuating the cutters.

6. A machine for cutting concave slots into the edges of structuremembers having convex edges for dovetailing purposes, comprising atable, a pair of relatively inclined cutting wheels mounted on thetable, means for carrying and supporting the structure members at rightangles to each other mounted on the table, means for periodically movingthe cutting means in a horizontal arc toward and away from the structuremembers at coincident spots and means for actuating the cutting means.

7. A machine as claimed in claim 5 comprising dual means forsynchronously operating the slide in a longitudinal direction and formoving the cutters toward and away from the members.

CARL PEDERSEN ASPELUND.

